Reusable frames for air filters

Abstract

Reusable frames for air filters, framed air filters, kits for making framed air filters, and methods of making and using framed air filters. The frame may include a frame base and a frame cover that are attached to each other to form the frame. The frame may include first and second opposing primary frame portions that respectively include first and second upward-open-ended elongate slots that are configured to receive first and second securing tabs of an expandable pleated air filter. The frame may include a set of upward struts that collectively form an upward anti-sag lattice with a multiplicity of anti-sag protrusions that protrude in a downward direction from a downward face of the upward anti-sag lattice.

What is claimed is: 
     
         1 . A reusable rectangular frame configured to receive a pleated air filter, the frame comprising:
 first and second opposing primary frame portions and first and second opposing secondary frame portions, the primary and secondary frame portions meeting at corners of the rectangular frame;
 wherein the first and second opposing primary frame portions respectively comprise first and second upward-open-ended elongate slots, each upward-open-ended elongate slot having a long axis that is aligned with a primary axis of the frame and having a slot depth in an upward-downward direction, with the first upward-open-ended elongate slot being configured to receive a first securing tab of a first primary end of a pleated air filter, and with the second upward-open-ended elongate slot being configured to receive a second securing tab of a second, opposing primary end of the pleated air filter, 
   the frame further comprising a set of upward struts that collectively form an upward anti-sag lattice and a set of downward struts that collectively form a downward support lattice,
 wherein the upward anti-sag lattice comprises a multiplicity of anti-sag protrusions that protrude in a downward direction from a downward face of the upward anti-sag lattice and that are spaced along a secondary direction of the frame, 
 and, 
 wherein the downward support lattice comprises an upward face that is planar without any protrusions that protrude in an upward direction from an upward face of the downward support lattice. 
   
     
     
         2 . The frame of  claim 1 , wherein the first and second opposing secondary frame portions respectively comprise first and second downward support flanges that respectively extend inward from downward ends of first and second opposing inward secondary sidewalls of the secondary frame portion so that a first inward edge of the first downward support flange defines a first secondary edge of a downward air-filtration area defined by the frame and a second inward edge of the second downward support flange defines a second secondary edge of the downward air-filtration area defined by the frame. 
     
     
         3 . The frame of  claim 2 , wherein the first and second secondary frame portions respectively comprise first and second upward anti-sag flanges that respectively extend inward from upward ends of the first and second opposing inward secondary sidewalls of the secondary frame portion so that a first inward edge of the first upward anti-sag flange defines a first secondary edge of an upward air-filtration area defined by the frame and a second inward edge of the second upward anti-sag flange defines a second secondary edge of the upward air-filtration area defined by the frame, and wherein each anti-sag flange comprises a multiplicity of anti-sag protrusions that protrude in a downward direction from a downward face of the upward anti-sag flange and that are spaced along a secondary direction of the frame. 
     
     
         4 . The frame of  claim 1  wherein the frame is a two-piece frame that comprises a first, downward frame base and a second, upward frame cover that are attached to each other to form the frame;
 wherein first and second opposing primary portions of the frame base respectively comprise the first and second upward-open-ended elongate slots; 
 wherein first and second opposing secondary portions of the frame base respectively comprise first and second downward support flanges that extend at least generally inward from downward ends of first and second opposing inward secondary sidewalls of the first and second secondary portions of the frame base so that first and second inward edges of the first and second downward support flanges respectively define first and second secondary edges of a downward air-filtration area defined by the frame base; and, 
 wherein the frame base comprises the set of downward struts that collectively form the downward support lattice and the frame cover comprises the set of upward struts that collectively form the upward anti-sag lattice. 
 
     
     
         5 . The frame of  claim 4  wherein first and second secondary opposing portions of the frame cover respectively comprise first and second opposing inward secondary sidewalls; and,
 wherein when the frame base and frame cover are attached to each other to form the frame, upward edges of the first and second opposing inward secondary sidewalls of the frame base and downward edges of the first and second opposing inward secondary sidewalls of the frame cover are abutted together at first and second inward secondary sidewall junctions so that the first and second opposing inward secondary sidewalls of the frame base and the first and second opposing inward secondary sidewalls of the frame cover, respectively combine to form first and second continuous planar opposing inward secondary sidewalls of the frame. 
 
     
     
         6 . The frame of  claim 5  wherein the first and second opposing primary portions of the frame base are double-walled with first and second opposing inward primary sidewalls and first and second opposing corrugated outward primary sidewalls that are outwardly spaced from the first and second opposing inward primary sidewalls;
 wherein the first and second opposing secondary portions of the frame base are double-walled with first and second opposing inward secondary sidewalls and first and second opposing corrugated outward secondary sidewalls that are outwardly spaced from first and second opposing inward secondary sidewalls; 
 wherein first and second opposing primary portions of the frame cover are single-walled so as to comprise only first and second opposing corrugated outward primary sidewalls; 
 and, 
 wherein first and second opposing secondary portions of the frame cover are double-walled with first and second opposing inward secondary sidewalls and first and second opposing corrugated outward secondary sidewalls that are outwardly spaced from the first and second opposing inward secondary sidewalls. 
 
     
     
         7 . The frame of  claim 4  wherein the frame base comprises a downward sealing apron with a downward face that is planar and that extends around the entire perimeter of the frame base and that has an outward edge, with the provisos that no portion of the frame base is positioned downward of the downward face of the downward sealing apron and that no portion of the frame base is positioned outwardly of the outward edge of the downward face of the downward sealing apron. 
     
     
         8 . The frame of  claim 7  wherein a central area of a first corrugated outward primary sidewall of a first primary portion of the frame cover comprises a first outward panel that defines a through-aperture configured to receive a finger for grasping the frame, with the proviso that no portion of the first outward panel is positioned outwardly of the outward edge of the downward face of the downward sealing apron. 
     
     
         9 . The frame of  claim 7  wherein first and second opposing corrugated outward primary sidewalls of the first and second opposing primary portions of the frame base each comprise a window in a downward section of the corrugated outward primary sidewall, each window being configured so that with a pleated air filter is installed in the frame base, an indicator zone of a downward section of a securing tab of the pleated air filter is visible through the window in the corrugated outward primary sidewall of the frame base. 
     
     
         10 . The frame of  claim 4  wherein the first upward-open-ended elongate slot of the frame base is inwardly bounded by a first inward primary sidewall of the first primary portion of the frame base and is outwardly bounded by a first outward primary sidewall of the primary portion of the frame base, the first inward primary sidewall being planar and the first outward primary sidewall being corrugated so as to comprise alternating inward and outward panels;
 wherein the first upward-open-ended elongate slot comprises sloped ribs that extend outwardly from the planar first inward primary sidewall and sloped ribs that extend inwardly from the first outward primary sidewall, with the outwardly-extending sloped ribs and the inwardly-extending sloped ribs being spaced, and alternating, along an elongate length of the elongate slot with the inwardly-extending sloped ribs each extending from an inward panel of the corrugated first outward primary sidewall and with the outwardly-extending sloped ribs each extending from an area of the first inward primary sidewall that is across from an outward panel of the corrugated first outward primary sidewall; 
 and, 
 wherein downward sections of the outwardly-extending sloped ribs comprise outward contact surfaces that are spaced inwardly from inward contact surfaces of downward sections of the inwardly-extending sloped ribs. 
 
     
     
         11 . The frame of  claim 4  wherein a upward-downward depth of the frame cover is within 20% of an upward-downward depth of the frame base; and, wherein first and second opposing corrugated outward secondary sidewalls of first and second opposing secondary portions of the frame cover respectively comprise first and second outwardly-deflectable, non-hinged latch members that are configured to engage first and second latch catches of first and second opposing corrugated outward secondary sidewalls of secondary portions of the frame base to attach the frame cover to the frame base. 
     
     
         12 . A kit comprising the frame of  claim 1 , the frame comprising a frame base and a frame cover that, in the kit, are attached to each other to form the frame, the kit further comprising at least two expandable pleated air filters, each pleated air filter being in the form of a pleatpack in which the pleated air filter is in a compacted condition and with each pleatpack being packaged within a pleated-air-filter-receiving receptacle defined within the frame. 
     
     
         13 . The kit of  claim 12  wherein the pleated air filter comprises an in-use pleat height and wherein a downward face of the upward anti-sag lattice of the frame cover and an upward face of the downward support lattice of the frame base are spaced apart along an upward-downward direction so as to define a depth of the pleated-air-filter-receiving receptacle; and, wherein the depth of the receptacle is from 94 to 99% of the in-use pleat height of the pleated air filter. 
     
     
         14 . A method of installing a pleated air filter in a reusable frame, the method comprising:
 inserting a first securing tab of a first primary end of a pleated air filter into a first upward-open-ended elongate slot of a first primary portion of a frame base;   expanding the pleated air filter along an expansion direction into an expanded, in-use condition;   inserting a second securing tab of a second, opposing primary end of the pleated air filter into a second upward-open-ended elongate slot of a second, opposing primary portion of the frame base, so that the pleated air filter is installed in the frame base;   then,   attaching a frame cover to the frame base to form a framed air filter comprising the reusable frame with the pleated air filter installed therein;
 wherein the frame cover comprises a set of upward struts that collectively form an upward anti-sag lattice and the frame base comprises a set of downward struts that collectively form a downward support lattice,
 wherein the upward anti-sag lattice comprises a multiplicity of anti-sag protrusions that protrude in a downward direction from a downward face of the upward anti-sag lattice and that are spaced along a secondary direction of the frame, 
 and wherein the downward support lattice comprises an upward face that is planar without any protrusions that protrude in an upward direction from an upward face of the downward support lattice. 
 
   
     
     
         15 . The method of  claim 14  wherein the method includes a further step of installing the framed air filter into a framed-air-filter-receiving receptacle of a powered air-handling apparatus chosen from the group consisting of an HVAC system and a room air purifier. 
     
     
         16 . The method of  claim 14  wherein with the pleated air filter installed in the frame to form the framed air filter, at least some upward pleat tips of the pleated air filter are in contact with at least some of the anti-sag protrusions of the frame cover so that if the framed air filter is positioned so that the expansion direction of the pleated air filter is vertically aligned, the anti-sag protrusions support the upward pleat tips to prevent the pleated air filter from sagging due to its own weight. 
     
     
         17 . The method of  claim 16  wherein the pleated air filter, when in its expanded, in-use condition, exhibits a pleat spacing along the expansion direction of the pleated air filter; and, wherein the anti-sag protrusions are spaced along the secondary direction of the frame at a spacing that is less than 80% of the pleat spacing of the pleated air filter. 
     
     
         18 . The method of  claim 14  wherein with the pleated air filter installed in the frame base, a downward section of the first securing tab of the pleated air filter is held in a friction-fit between outward contact surfaces of outwardly-extending ribs of the frame base and inward contact surfaces of inwardly-extending ribs of the frame base, in the first upward-open-ended elongate slot of the first primary portion of the frame base. 
     
     
         19 . The method of  claim 14  wherein with the pleated air filter installed in the frame base, an indicator zone of a downward section of the first securing tab of the pleated air filter is visible through a window in a downward section of an outward primary sidewall of the first primary portion of the frame base. 
     
     
         20 . The method of  claim 14  wherein the pleated air filter comprises at least two pleat-spacing-limiting elongate members that are located on an upward side of the pleated air filter, that extend at least generally along the expansion direction of the pleated air filter, that are spaced apart along a pleat direction of the pleated air filter, and that are bonded to upward pleat tips of the pleated air filter; and, wherein the anti-sag protrusions on the downward face of the upward anti-sag lattice are positioned so that with the pleated air filter installed in the frame, none of the anti-sag protrusions contact any of the pleat-spacing-limiting elongate members. 
     
     
         21 . The method of  claim 14  wherein the frame base comprises a downward sealing apron with a downward face that is planar and that extends around the entire perimeter of the frame base, and wherein with the framed air filter installed in the framed-air-filter-receiving receptacle of the powered air-handling apparatus and the powered air-handling apparatus operating, air pressure generated by the powered air-handling apparatus urges the downward face of the downward sealing apron of the frame base against an upward-facing seating surface of the framed-air-filter-receiving receptacle of the powered air-handling apparatus so as to at least substantially prevent air from bypassing the framed air filter.